In order to contact a semiconductor layer, covered with one or more further semiconductor layers, of a semiconductor layer sequence, one or more through-connections, so-called vias, may be used, which extend through the covering semiconductor layers to the semiconductor layer to be contacted. These through-connections are conventionally openings in the semiconductor layer sequence in the form of blind holes which project through a part of the semiconductor layer sequence and which are filled with an electrically conductive material. To prevent a through-connection short-circuiting the semiconductor layers through which it passes, the sidewalls of the openings in which through-connections are arranged are conventionally provided with an electrically insulating layer, such that, within the semiconductor layer sequence, the through-connection is in electrical contact only with the semiconductor layer to be contacted.
To produce a through-connection, therefore, firstly an opening has to be produced in the semiconductor layer sequence. Secondly, the sidewalls of the opening need to be provided with an electrically insulating layer, wherein that part of the opening in which the semiconductor layer to be contacted lies exposed must be at least partly free of the electrically insulating layer. These two steps are conventionally performed in the prior art using photoresist masks and with the assistance of two separate photo levels. This means that one photomask is used to produce the openings in the semiconductor layer sequence and then a further photomask is used to pattern the electrically insulating layer in such a way that the openings in the region of the semiconductor layer to be contacted are at least partially free of the electrically insulating layer. For this purpose, extremely accurate and thus complex process control is needed, since the second photomask requires very high precision.